摘要
近几年鄂尔多斯盆地东南部上古生界陆续发现新的天然气区带,显示出巨大的勘探潜力,因此在盆地东南部上古生界进行物源、沉积相、砂体展布规律的研究具有重要价值。以钻测井、岩芯及周边露头资料为基础,通过露头剖面古流向测定、重矿物分析及相带分析的方法,确定了研究区二叠系的物源方向;分析了上古生界沉积相类型,揭示了骨架砂体平面展布特征。研究认为:山西组与石盒子组物源可分为北北东、北北西及南部三个方向;本溪组主要发育障壁岛—潟湖及潮坪沉积,海侵方向来自东部,由沉积相控制的本溪组障壁岛砂体呈北北东向展布;山2、山1、盒8段主体发育不同来源方向的三角洲前缘沉积,受物源方向及沉积相控制,以延安为中心区域主体属于汇水区,骨架砂体分别由四个向延安区域汇聚的北北西、北北东、南南东向及南部三角洲前缘水下分流河道朵体组成,在汇水区不同方向来源砂体在不同层段具有相互叠置特征;山2段南部物源砂体较发育,盒8段北部物源砂体较发育,反映研究区古构造从南高北低转换为北高南低,指示鄂尔多斯盆地在山西组与石盒子组之间发生了南北向构造反转。
In recent years,lots of new gas plays are found continuously in the Upper Paleozoic in southeast Ordos basin,which displays great exploration prospects.The Upper Paleozoic was influenced by multisource in the former study,while the main provenance was from north.It is not clear that whether there was sourthern provenance,how much the influenced area was,and what degree the influence was,which greatly influenced gas exploration strategy in the study area.Since lithologic play is the main reservoir in Ordos basin,the study on source and the rule of depositional facies on Upper Paleozoic sandbody distribution is of great importance in southeast Ordos basin.Based on data of well drilling,logging and core as long with outcrop sections of surroundings,by means of paleocurrent direction measuring in outcrop sections,heavy mineral analyzing as well as facies belt diagnosing,the provenance directions of the Permian are confined,the depositional facies styles of the Upper Paleozoic are analyzed,the rule of source,geography of depositional basement and depositional facies on sandbody distributions in the study area are studied,and also the distribution feature of skeleton sandbody are disclosured.Based on the above studies the following conclusion can be obtained.Paleocurrent direction revealed the whole middle part of the study area was catchment area in periods of Shanxi and Shehezi Formation,which suggests the possible existence of north and south of two different sources in the very time.Heavy mineral analyzing indicated that the NNE region of the studied area is rich in zircon,the NNW region of the studied area is mixed area of zircon,leucoxene and garnet,while the south region is rich in leucoxene,which disclosures that the provenance of Shanxi and Shehezi Formation can be divided into three directions which are NNE,NNW,and south.The coast line and geography of deposit basement reflected by thickness of strata and limestones indicated transgression direction being from east.Benxi Formation mainly developed barrier island ＆ lagoon and tidal flat facies,the distribution of barrier island and tidal channel sandbodies were controlled by geography of deposit basement and depositional facies belts with the barrier sandbody being distributed along NNE direction.Depositional facies belts of Shanxi and Shehezi Formation were controlled by the orientation of provenance,which controlled the distribution of under water lobate distributary channels.Shan 2,Shan 1 and He 8 Member mainly developed delta front depositional facies sourced from different directions which were controlled by provenance directions and depositional facies belts,while Yan’an region being the center of water catchment.The skeleton sandbodies are composed of four under water lobate distributary channels converging to Yan’an region coming from NNE,NNE,and SSE as well as south direction,different sourced sandbodies in different layers display the style of overriding in water catchment area.The skeleton sandbodies sourced from south developed well in Shan-2 member,which influenced areas of north of Yanan,while the skeleton sandbodies sourced from north developed well in He 8 member,which overreached areas of south of Yanan while the southern provenance receded simultaneously,reflecting that palaeo-terrain in the studied area conversed from south being higher than north to north being higher than south,and also indicating that constitution reversed along NS direction in Ordos basin between periods of Shanxi and Shehezi Formation.
出处
《沉积学报》
CAS
CSCD
北大核心
2011年第5期825-834,共10页
Acta Sedimentologica Sinica
基金
国家科技重大专项(编号:2008ZX05025-006)
国家重点基础研究发展规划"973"项目(编号:2009CB219400)资助
关键词
鄂尔多斯盆地
上古生界
古流向
物源
沉积相
砂体
Ordos basin； the Upper Paleozoic； paleo-current directions； Provenance； depositional facies； sandbody
作者简介
屈红军 男 1967年出生 博士教授 沉积学与盆地分析 E-mail：hongjun@nwu．edu．cn
